This invention relates to organosilicon compositions and more particularly to polyolefin filled-organopolysiloxane compositions.
Heat vulcanizable and room temperature vulcanizable polyorganosiloxane compositions are well known. Generally, these compositions, whether they be of the one-package or two-package type, are composed of an organopolysiloxane base material, crosslinking agents, such as alkyl silicates, alkyltriacyloxysilanes, etc., and curing or crosslinking catalysts, such as organic peroxides, metals salts of carboxylic acids, etc.
It is also well known to incorporate various additives into these organopolysiloxane compositions to improve their properties. Included among these additives are inorganic filler materials, such as silica aerogel, diatomaceous earth, calcium carbonate, iron oxide, etc. The use of filler materials of this nature, however, has not met with complete satisfaction, since often the improvement in the properties of the organopolysiloxane composition realized by their presence may be outweighed by the high cost and formulation problems which they present. This is particularly the case when employing certain silica fillers.
Other methods to improve the properties of organopolysiloxane compositions have also been used in the past. For example, U.S. Pat. No. 2,965,593 to Dietz discloses that a water-repellant polyorganosiloxane composition is provided by dispersing a polyorganosiloxane in a vinyl monomer base and polymerizing the mixture. The resultant material is disclosed therein as a mixture of the polyorganosiloxane in a thermoplastic high polymer matrix.
Further attempts to improve the properties of the organopolysiloxanes are disclosed, for example, in U.S. Pat. Nos. 3,631,087, 3,627,836, 3,580,971, 3,441,537, 3,436,252, 3,070,573, 2,959,569 and 2,958,707. These patents disclose the use of grafted organopolysiloxanes, i.e., organopolysiloxanes which are chemically grafted with polymeric side chains. As discussed, for example, in U.S. Pat. No. 3,627,836, while graft-modified polymers have some desirable properties, they are inadequate in others, and accordingly have not met with total satisfaction.